"Bob" wrote in message
news:8Evef.21536$5R4.8753@trnddc06...
Steven Fritts wrote:
Hello All,
I picked up a really nice working Swan 350 at a hamfest this past
weekend. I bought it for nostalgic reasons as it was the kind of rig
my dad bought for me in 1965. I need info on how to fix the infamous
"Swan drift problem". Anyone have any websites I can go to get mods
for this rig including the drift fix?
Any help will be appreciated!

Steve W4SEF
The problem is, for the most part, lack of proper temperature
compensation. Sure, the voltage regulation isn't that great, but it's not
the main problem.

Looking at the diagram for the VFO you can see the tuned circuit
components. You can add a negative temperature coefficient capacitor to
the circuit to compensate for the (usually) positive coefficients of the
parts.

I did this successfully in a Viking Valiant. I reduced the drift from
about 10kHz or more on 10 meters to about 1kHz. One thing I did was move
a hot resistor out of the VFO compartment to reduce the amount of
temperature rise of the critical parts.

You can also leave the unit on, at least the VFO, at all times so the
temperature will be more stable.

73, Bob K6DDX


While most tube rigs will drift *some*, I found that turning on my Swan
700CX about 30-45 minutes before using it did a LOT to reduce drift. I
think, too, that newer hams, not being familiar with the old tube rigs, are
more critical than those of us who are familiar with them. I hear people
putting down Swans ("I HATE them old Swans cuz they drift"), but it isn't
all *that* bad! I mean, just think, what did we DO back in the glowing
tube days, right? If it had been THAT bad, we'd not been able to function.
Sure---Swans drift and have a reputation for it, but I owned 3 of them and
never had THAT much trouble. I HAVE had worse!

73

Jerry